The Prison the Real Billy Hayes was incarcerated in is now a luxury hotel.

The movie prison was actually much more primitive. It was filmed at the famous Fort St. Elmo in Malta.

If you are ever in Turkey you can sleep in the same prison as Billy Hayes and get room service. Hopefully they won't send Rifki or Hamidou up with your meal.

https://www.fourseasons.com/istanbul/

https://en.wikipedia.org/wiki/Sultanahmet_Jail